1. Field of the Invention
Embodiments of the present invention relate to an apparatus, medium, and method with automatic white balance control capable of detecting accurate light sources by minimizing a chromatic component introduced into a gray region and automatically controlling a white balance based on detected light source information having the color component being extracted from a chromatic color space.
2. Description of the Related Art
White balance control refers to a color control function of adjusting a color balance in a captured image or video by a shift of overall color tones through a detecting of the white color suffering the largest changes to an object color, due to light sources in an input image data, deciding a color temperature by RGB component ratios of the detected white color, and controlling red and blue colors R and B, according to the color temperature, and based on the detected white color.
Generally, even when an identical object is image-captured by an imaging apparatus such as a digital still camera, digital video camera, or the like, the captured image colors look different depending on circumstances surrounding various related image light sources, such as an incandescent room lamp, fluorescent lamp, sun light, or the like. Human eyes have color constancy enabling humans to sense a white color, as the white color, by adapting the eyes to each light source, but an imaging apparatus reproduces white color such that a blue color is included when the color temperatures of the light sources are high or a red color is included when the color temperatures are low, since RGB components are reflected by the light sources having different color temperatures.
Accordingly, white balance control is needed in order for a white color to be properly sensed as the white color, e.g., when the color temperature changes due to changes in light sources. For example, a white color containing a blue color may need to be controlled such that the gain of a red color R is increased and the gain of the blue color B is decreased, or a white color containing a red color may need to be controlled such that the gain of the blue color B is increased and the gain of the red color R is decreased.
Such an accurate control over the white balance requires an accurate detection of a reference white color. For this purpose, the white balance can be controlled based on a gray world assumption, stating that integrating whole color components of a captured image results in a zero, that is, a color close to an achromatic color. Specifically, white balance control under the gray world assumption can effectively detect a white color if an input image has a wide range of diverse colors. It is necessary in white balance control, under the gray world assumption, to accurately control white balance with acquisition of accurate information about light sources even when there exists a dominant color in an input image or a chromatic component is introduced into an extracted gray region.